The inflammatory response is a complex defensive reaction in vertebrates to infection or injury caused by chemical agents, pathogens, or physical stresses. The complexity of the inflammatory response is illustrated by the “immune cascade” that occurs in response to infection. Macrophages and dendritic cells at the insult site express surface receptors that identify infectious agents. Upon encountering an infectious agent, these cells release inflammatory mediators (soluble factors) such as cytokines and chemokines, which cause vasodilation and exudation of plasma proteins and fluid into the affected tissue. Inflammatory mediators also attract and facilitate transport of leukocytes such as neutrophils, lymphocytes, monocytes, and macrophages from the blood vessels into the affected tissue. The inflammatory response is further assisted by the activation of cellular biochemical cascade systems, including the complement, coagulation, fibrinolytic, and kinin systems.
Acute inflammation is an essential component of wound healing, but chronic inflammation can cause tissue destruction and lead to conditions such as cardiovascular disease, neurodegeneration, and autoimmunity. Inflammatory conditions associated with chronic inflammation are highly prevalent, creating a significant economic burden and leading to low quality of life for affected individuals. A variety of anti-inflammatory agents are available for treating these conditions, but most of these agents are administered systemically and are associated with side effects such as increased infection.